Electrically powered vehicles, such as hybrid vehicles, electric vehicles, etc., are each mounted with a power storage device (representatively, a secondary battery) for storing power inputted to and outputted from a traction motor.
Japanese Patent Laying-Open No. 2010-166790 (PTD1) describes a configuration wherein a plurality of high-voltage batteries are connected in parallel, allowing power to be supplied to a boost converter serving as an on-board power converter circuit. With the configuration described in PTD1, the boost converter enables variable control of DC-side voltage of an inverter, i.e., amplitude of pulse voltage applied to the motor for traveling.
As another example in which a plurality of power storage devices are connected, Japanese Patent Laying-Open No. 2010-110124 (PTD2) discloses a power supply system mounted with a main secondary battery block and an auxiliary secondary battery block. The power supply system disclosed in PTD2 is provided with a DC-DC converter for converting output voltage of the auxiliary secondary battery block. PTD2 also describes that the DC-DC converter up-converts voltage from the auxiliary secondary battery block during discharge for supply of power to a load, and down-converts voltage from the main secondary battery block during charge for supply of power to the auxiliary secondary battery block.